In providing electrical power service and telephone service to a building, separate electrical grounding systems are typically provided for each type of service. For example, an electrical utility box containing a meter will have a riser or ground level connector which supplies power to the building. An elongated ground rod is sunk into the ground and connected through heavy gauge wire to the electrical utility box for grounding purposes.
Adjacent to the electric utility box may be the telephone system interface box. The telephone system interface box is typically connected through a riser to the telephone line from the telephone company. Again, a separate elongated ground rod will be sunk, typically within several feet of the power ground rod, and run through wire of lower gauge to the telephone system interface box for grounding purposes.
To reduce the potential difference between the telephone wiring and the electrical system, it is then necessary to connect a jumper wire or bond between the telephone system ground rod and the electrical power system ground rod to prevent differences in potential which could result in uncontrolled arcing between the telephone wiring and the electrical system in the event of lightning or accidental contact with the telephone line, for example.
While the foregoing procedures provide adequate grounding of the power system and telephone system and reduce potential differences therebetween, the cost and complexity is high in that two pairs of grounding rods, clamps, grounding wires as well as the ground jumper wire or bond are required. All these various elements require installation, in addition to the cost and complexity of the hardware itself.
A single grounding system would be desirable, but has proved elusive. The telephone ground rod is typically of much smaller diameter and length than the power ground rod and could not adequately handle the more substantial requirements for the power system. The power ground rod is buried and the available metal conductors such as the utility meter box are painted and/or treated with a coating &o prevent rusting and provide for long term life. Further, drilling a hole through the electric utility box is highly undesirable in that entry of foreign matter and moisture into the electric utility box is then allowed. Any system must recognize the realities of adverse conditions including dirt, paint, and other non-conducting surfaces, as well as corrosion, which must be addressed in order to insure a suitable mechanical and electrical connection which will withstand the rigors of an outdoor environment.
Various clamping devices have been known in the art to provide an electrical ground. These include C-clamps and various forms of strap connectors. However, it has not been apparent that any of the known clamping devices could overcome the problems inherent in the current system of providing separate grounding systems for the electrical power system and the telephone system.